I'm somewhere in between the two camps. When I first quit using the statement "I will never drink again in my life" seemed waaay too overwhelming. What I could say is I will not drink today. Or during some of the truly challenging times in the beginning, I will not drink in the next hour. And that got me through to the next day. It's now much, much easier on a daily basis and I'm able to see it as a long term commitment. Still not using the phrase "for life".
However I don't believe if a person relapses it means "their methods of self-reliance have failed". I believe it means addiction is something we must remain vigilent about. Always.
The same thing applies to other addictions, cigarettes in my case. I quit for a week then went back to it. I now know I can get past the initial torture and it does indeed get easier on the other side, which is more than I knew going into it the first time. Next time I'll make it further. Not ideal but yes it is what it is.